The present invention relates to method and apparatus for assembling and disassembling a stator winding of a dynamo-electric machine particularly adapted for field-work in an electric power plant at a time of changing stator windings each having heavy weight.
In general, a stator winding and other components of a dynamo-electric machine are assembled through complicated processes, and in a manufacturing plant, these components are assembled by using dedicated crane and conveying apparatus, or specific apparatus. However, in recent years, there is increased cases where an insulating performance of the stator windings has been degraded in accordance with time elapsing and, hence, the stator windings are to be changed with new ones.
FIG. 10 shows a general structure of a stator of a dynamo-electric machine, FIG. 11 shows an outer appearance of a stator winding, and FIG. 12 is a perspective view for explaining assembling the stator winding to the stator core at the working field.
Referring to these figures, a stator frame is denoted by a reference numeral 1 and a reference numeral 2 denotes a stator core, to which are formed a plurality of slots 3 into which lower and upper stator windings 4 (4aand 4b) are inserted. Stator winding wedge members 8 are further inserted into the slots 3, outside these stator windings 4a and 4b, for fixing them assembled in the slots 3. These windings each has relatively heavy weight.
FIG. 13 shows a flow-chart showing steps of an actual field working, and with reference to this figure, stator winding assembling steps are described hereunder.
First, a temporary housing is settled at a portion external of the stator frame, generally, on a collector side, and a temporary setting table 6 is located in the temporary housing 5 (steps A1 and A2).
In a case where a generator having the stator core 2 having a large diameter is handled, as shown in FIG. 12, a scaffold 7 is arranged so that a plurality of workers can enter into the stator core 2 (step A3).
Upon the completion of these preliminary steps, the stator winding wedge members 8 are removed from the slots 3 by the workers in a narrow space inside the stator core 2 before disassembling the stator windings 4. Temporary wedge members 9 are ones which are temporarily inserted into the slots 3 after the removal of the stator winding 4a (step A4). Thereafter, the heavy upper stator windings 4a are carried by the workers out of the stator frame 1, or the heavy upper stator windings 4a are suspended down from the slots and withdrawn one by one from the slots 3 and conveyed out by the workers along the axially longitudinal direction of the stator core 2 (step A5).
After the disassembling of the upper stator windings 4a in all the slots 3 has been completed, the lower stator windings 4b are then disassembled and conveyed out of the stator frame 1 by the workers (step A6).
It is natural, without further comment, before the disassembling of these stator windings 4, to disconnect, cut or decompose electric connection or mechanical connection between end portions of the respective stator windings 4.
When new stator windings 4 are composed or assembled, necessary numbers of the new stator windings 4 are conveyed on the temporary setting table 6 at respective times and the lower stator windings 4b are first carryed and inserted into the slots 3 in the stator core 2 by the workers (step A7). Then, the upper stator windings 4a are inserted into the slots 3, respectively, and thereafter, the stator winding wedge members 8 are piled into the slots 3 for fixing the stator windings 4 (4a, 4b) therein (steps A8 and A9).
However, in the disassembling working of the stator windings as mentioned above requires physically hard workings for the workers and also involves dangerous workings, including suspension working, conveying working, or the like because the heavy stator windings are handled in a narrow space inside the stator core by many workers.
That is, the stator winding of a dynamo-electric machine of large capacity each generally has a weight of about 980-1981 N(Newton), and moreover, there are many restrictions for the working environment in the narrow inside space of the stator core. When the workers work in such narrow inside space of the stator core, it is necessary for the workers to take an unnatural attitude for conveying in or out the heavy windings and the like, which is dangerous and requires severe physical conditions for the workers for suspending, conveying or handling of the heavy windings in the stator core. Therefore, in the prior art, the disassembling and assembling of the stator windings requires much time and much labor for many workers in a severe environmental condition, providing significant problems.